trim

(PHP 4, PHP 5)

trimRimuove gli spazi (ed altri caratteri) all'inizio e alla fine di un testo

Descrizione

string trim ( string $str [, string $charlist ] )

Questa funzione restituisce il parametro str privo degli spazi iniziali e finali. Senza la specifica del secondo parametro, trim() rimuoverà questi caratteri:

  • " " (ASCII 32 (0x20)), spazio.
  • "\t" (ASCII 9 (0x09)), il carattere tab.
  • "\n" (ASCII 10 (0x0A)), il new line (line feed).
  • "\r" (ASCII 13 (0x0D)), il carriage return.
  • "\0" (ASCII 0 (0x00)), il byte NUL.
  • "\x0B" (ASCII 11 (0x0B)), il tab verticale.

Elenco dei parametri

str

La stringa che deve essere troncata.

charlist

Opzionale, Si può, inoltre, specificare quali caratteri si desidera rimuovere elencandoli in charlist. Questo parametro è un semplice elenco dei caratteri da rimuovere. Con .. si può indicare un range di caratteri.

Valori restituiti

La stringa troncata.

Log delle modifiche

Versione Descrizione
4.1.0 E' stato aggiunto il parametro opzionale charlist.

Esempi

Example #1 Esempio di uso di trim()

<?php

$text 
"\t\tThese are a few words :) ...  ";

echo 
trim($text);           // "These are a few words :) ..."
echo trim($text" \t.");   // "These are a few words :)"

// rimuove i caratteri di controllo ASCII all'inizio ed alla fine di $binary
// (da 0 a 31 compresi)
$clean trim($binary"\x00..\x1F");

?>

Example #2 Trimming array values with trim()

<?php
function trim_value(&$value)
{
  
$value trim($value);
}

$fruit = array('apple','banana '' cranberry ');
var_dump($fruit);

array_walk($fruit'trim_value');
var_dump($fruit);

?>

Il precedente esempio visualizzerà:

array(3) {
  [0]=>
  string(5) "apple"
  [1]=>
  string(7) "banana "
  [2]=>
  string(11) " cranberry "
}
array(3) {
  [0]=>
  string(5) "apple"
  [1]=>
  string(6) "banana"
  [2]=>
  string(9) "cranberry"
}

Vedere anche:

  • ltrim() - Rimuove gli spazi (o altri caratteri) dall'inizio di una stringa
  • rtrim() - Rimuove gli spazi (ed altri caratteri) dalla fine della stringa

add a note add a note

User Contributed Notes 14 notes

up
17
ludko2 at gmail dot com
4 years ago
Non-breaking spaces can be troublesome with trim:

<?php
// turn some HTML with non-breaking spaces into a "normal" string
$myHTML = "&nbsp;abc";
$converted = strtr($myHTML, array_flip(get_html_translation_table(HTML_ENTITIES, ENT_QUOTES)));

// this WILL NOT work as expected
// $converted will still appear as " abc" in view source
// (but not in od -x)
$converted = trim($converted);

// &nbsp; are translated to 0xA0, so use:
$converted = trim($converted, "\xA0"); // <- THIS DOES NOT WORK

// EDITED>>
// UTF encodes it as chr(0xC2).chr(0xA0)
$converted = trim($converted,chr(0xC2).chr(0xA0)); // should work

// PS: Thanks to John for saving my sanity!
?>
up
16
jubi at irc dot pl
10 years ago
To remove multiple occurences of whitespace characters in a string an convert them all into single spaces, use this:

<?

$text = preg_replace('/\s+/', ' ', $text);

?>

------------
JUBI
http://www.jubi.buum.pl
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4
Piopier
7 years ago
It may be useful to know that trim() returns an empty string when the argument is an unset/null variable.
up
2
Hayley Watson
9 years ago
Another way to trim all the elements of an array
<?php
$newarray
= array_map('trim', $array);
?>
up
0
david at rayninfo dot co dot uk
18 days ago
Trim will generate a warning is you try to trim an empty string if this is a problem for you can test with is_string
up
0
tomdudman at gmail dot com
9 months ago
This function trims regular expressions from strings.

<?php
   
function preg_trim( $string, $pattern ) {
       
$pattern = array( "/^" . $pattern . "*/", "/" . $pattern . "*$/" );
        return
preg_replace( $pattern, "", $string );
    }
?>

The following example outputs "Hello, world":

<?php
    $hello
= "   ...%20Hello, world!";
    echo
preg_trim( $hello, "[^a-zA-Z]" );
?>
up
0
tbm.at.home.dot.nl
12 years ago
Windows uses two characters for definining newlines, namely ASCII 13 (carriage return, "\r") and ASCII 10 (line feed, "\n") aka CRLF. So if you have a string with CRLF's, trim() won't recognize them as being one newline. To solve this you can use str_replace() to replace the CRLF's with with a space or something.

<?php
// string with bunch of CRLF's
$my_string = "Liquid\r\nTension Experiment\r\n\r\n\r\n";

// replace CRLF's with spaces
$my_wonderful_string = str_replace("\r\n", " ", $my_string);
// would result in "Liquid Tension Experiment   "

// or just delete the CRLF's (by replacing them with nothing)
$my_wonderful_string = str_replace("\r\n", "", $my_string);
// would result in "LiquidTension Experiment"
?>
up
-2
josecruz at josecruz dot com dot br
5 years ago
A simple function to clear extra white spaces along a string.
<?php
function TrimStr($str)
{
   
$str = trim($str);
    for(
$i=0;$i < strlen($str);$i++)
    {

        if(
substr($str, $i, 1) != " ")
        {

           
$ret_str .= trim(substr($str, $i, 1));

        }
        else
        {
            while(
substr($str,$i,1) == " ")
          
            {
               
$i++;
            }
           
$ret_str.= " ";
           
$i--; // ***
       
}
    }
    return
$ret_str;
}
?>

[EDIT BY danbrown AT php DOT net: Contains a fix provided by (info AT deep-soft DOT com) to address the issue where "it deletes the first char after spaces (because of while)."]
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-2
dmr37 at cornell dot edu
9 years ago
If you want to check whether something ONLY has whitespaces, use the following:

<?php

if (trim($foobar)=='') {
   echo
'The string $foobar only contains whitespace!';
}

?>
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-4
seyednaser at gmail dot com
2 years ago
To show off the empty positions in a string by means of trim():

<?php
    $string
= "    Hello World!   ";
    echo
$string;
    echo
" Has : ".strlen($string)." letter(s). One by one according to the following:<br />";
    echo
"<br />".$rightt = strlen(ltrim($string)) - strlen(trim($string))." empty position(s) from right.";
    echo
"<br />".$leftt = strlen(rtrim($string)) - strlen(trim($string))." empty position(s) from left.<br />";
   
$length = strlen($string);
    for(
$x = 0; $x < $length; $x++){
   
$letter = substr($string, $x, 1);
        if(
$letter <> " ")
            echo
"<br />Position&nbsp;&nbsp; $x ===> &nbsp;&nbsp;".substr($string, $x, 1);
        else
            echo
"<br />Position&nbsp;&nbsp; $x ===> &nbsp;&nbsp; Empty";
    }   
?>

the output is:

Hello World! Has : 19 letter(s). One by one according to the following:

3 empty position(s) from right.
4 empty position(s) from left.

Position   0 ===>    Empty
Position   1 ===>    Empty
Position   2 ===>    Empty
Position   3 ===>    Empty
Position   4 ===>   H
Position   5 ===>   e
Position   6 ===>   l
Position   7 ===>   l
Position   8 ===>   o
Position   9 ===>    Empty
Position   10 ===>   W
Position   11 ===>   o
Position   12 ===>   r
Position   13 ===>   l
Position   14 ===>   d
Position   15 ===>   !
Position   16 ===>    Empty
Position   17 ===>    Empty
Position   18 ===>    Empty
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-5
gerjoo at gmail dot com
3 years ago
On my application I had several users submit what to me appeared as "empty strings", whereas in fact they were submitting the &shy; character.

Trim, by default, does not strip this character (Though arguably it should). The following code strips this character from your input:

<?php

// As the &shy; character is invisible we'll simply use the ASCII numeric representation, and decode via chr():
$string = trim($string, chr(173));

// If you wish to strip all occurences this will work:
$string = str_replace(chr(173), "", $string);

?>

Gerard
up
-6
syn-attack at devilzc0de dot org
1 year ago
I think this is my implementation of trim...

<?php
   
/*
     * Function: "trim"
     * @str = source
     * @charlist = list of characters to be trimmed from the source
     *
     * Author: syn-attack@devilzc0de.org
     * Full documentation in http://php.net/manual/en/function.trim.php
     */
   
function __trim($str, $charlist = '') {
       
$result = '';
       
/* list of forbidden chars to be trimmed */
       
$forbidden_list = array(" ", "\t", "\r", "\n", "\0", "\x0B");
       
        if (empty(
$charlist)) {
            for (
$i = 0; $i < strlen($str); $i++) {
                if ((
$str[$i] != $forbidden_list[0]) &&
                    (
$str[$i] != $forbidden_list[1]) &&
                    (
$str[$i] != $forbidden_list[2]) &&
                    (
$str[$i] != $forbidden_list[3]) &&
                    (
$str[$i] != $forbidden_list[4]) &&
                    (
$str[$i] != $forbidden_list[5])) {
                   
$result .= $str[$i];
                }
            }
        }
        else if (!empty(
$charlist)) {
           
$is_not_same = true;
           
            for (
$i = 0; $i < strlen($str); $i++) {
                for (
$j = 0; $j < strlen($charlist); $j++) {
                    if (
$str[$i] != $charlist[$j]) {
                       
$is_not_same = true;
                    }
                    else if (
$str[$i] == $charlist[$j]) {
                       
$is_not_same = false;
                        break;
                    }
                }
               
                if (
$is_not_same == true) {
                   
$result .= $str[$i];
                }
            }
        }
       
        return (
$result);
    }
   
   
$str = "Paulus Gandung Prakosa";
    echo
__trim($str);
?>
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-7
HW
11 years ago
You can combine character ranges and individual characters in trim()'s second argument (ditto for ltrim and rtrim). All of the specified characters and ranges will be used concurrently (i.e., if a character on either end of the string matches any of the specified charaters or character ranges, it will be trimmed). The characters and character ranges can be in any order (except of course that the character ranges need to be specified in increasing order) and may overlap.
E.g., trim any nongraphical non-ASCII character:
trim($text,"\x7f..\xff\x0..\x1f");
up
-6
Anonymous
8 months ago
if (preg_match('/[^\d]/', $pytanie_pomoc)) {
            throw new exception('special chars exists or spaces!.');
        }
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